Management of asymptomatic aortic stenosis: masterly inactivity but cat-like observation.

In patients presenting with symptoms, the natural history of significant aortic stenosis is unfavourable and the prognosis is dramatically improved by valve replacement. 1-3 However, some patients remain entirely free from symptoms despite severe outflow obstruction. When these asymptomatic patients are discovered incidentally it is often assumed that their outcome will be improved by surgery. We investigated whether there was any evidence in the literature to support this supposition. Patients with aortic stenosis are usually cate-gorised according to haemodynamic severity of outflow obstruction. This assessment is important because of its influence on prognosis in symptomatic patients.4 It is best estimated by measuring aortic valve area, either at cardiac catheterisation by Gorlin's formula or non-invasively with echocardiography. The use of aortic valve gradients alone (either Doppler or catheter derived) is inaccurate because it ignores cardiac output.5 6 If a gradient is found to be borderline or low, this may result from low output and the valve area should be measured. For practical purposes and for the content of this review, "severe" aortic stenosis is indicated by a valve area of < 0.9 cm2, by a catheter derived peak gradient of > 60 mm Hg or by a Doppler derived instantaneous gradient of > 60 mm Hg. Acquired aortic stenosis is characterised by a long asymptomatic stage, lasting for decades. Up to 30% of patients with severe aortic stenosis are asymptomatic,4 7-9 and some patients can remain symptom free even with an aortic valve area < 0-5 cm2. 0 In 1937 Contratto and Levine drew attention to the prognostic importance of symptoms11; they assessed severe aortic stenosis clinically, radi-ographically, and at necropsy and noted a short life expectancy only once the major symptoms of angina, syncope, and dyspnoea developed. Ross and Braunwald in 1968 estimated that only 3-5% of sudden deaths in acquired aortic stenosis occurred in patients without symptoms.' The crucial issue of when (if at all) to refer asymptomatic patients for surgery requires the mortality and long term complications associated with aortic valve replacement to be weighed against their risk of death on conservative treatment. The most current and accurate data for survival after aortic valve replacement (albeit for both stenosis and regurgitation) are available from the United Kingdom Heart Valve Registry 1994 report, which quotes 30 day survival at 95-6%, one year survival at 91-7%, and five year survival at 81-3%. These figures are for all cases and refer …